The present invention relates to a method of optimizing a mail sorting process.
Mail sorting machines are known which receive a randomly arranged stream of mail items at the input, and supply a sequenced stream of mail items at the output, i.e. a stream of mail items arranged in a predetermined order enabling sequential delivery by one or more postmen, each assigned a particular route.
More specifically, known sorting machines normally comprise an input receiving a mail batch, i.e. a group of mail items for sorting; a number of outputs, which may have respective containers for respective groups of mail items; and a sorting device interposed between the sorting machine input and outputs, and controlled by an electronic processing unit for directing each mail item to a respective output on the basis of a code, normally impressed on the mail item, and a table correlating the code to a given machine output.
The order in which the mail items in each batch are fed to the machine outputs may be defined, for example, by a sequence of adjacent delivery locations or destinations corresponding to address numbers, or groups of address numbers, of buildings along the delivery route of the mail items in that particular batch.
Each operative delivering the mail items in the batch is assigned a distinct group of machine outputs from which the assigned mail items are removed at the end of the sorting process.
A generic sorting process performed by the machine on a given mail batch normally comprises a number of sorting cycles by which groups of mail items are fed repeatedly and in orderly manner back into the machine input, and directed to outputs from whose containers the mail items deposited in the previous cycle have been removed.
More specifically, in the first cycle in the sorting process, the mail items are fed into the machine input and sorted into the outputs according to a first given criterion. The mail items are then removed in orderly manner from the outputs and fed back into the machine input in a predetermined order to perform a second sorting cycle, and so on up to the last sorting cycle, in which the mail items are sorted into the outputs according to an nth given criterion, and are then removed from the outputs, e.g. for actual delivery.
At the end of the sorting cycles, the groups of mail items coming of f the sorting machine are arranged in a predetermined order enabling sequential delivery by an operative assigned a subsection of a predetermined route.
The maximum number of delivery locations the sorting machine can handle in a given sorting process depends on the number of machine outputs available for the sorting process and the number of cycles in the sorting process, and, in particular, equals a value NUNC, where NU is the total number of machine outputs available for the sorting process, and NC the number of cycles in the sorting process.
In certain operating conditions, the relationship between the maximum number of delivery locations that can be handled by the machine in a given sorting process, the number of machine outputs available for the sorting process, and the number of cycles in the sorting process, may result in inefficient utilization of the sorting machine.
More specifically, situations may arise in which the number of delivery locations to be addressed is slightly higher than the maximum number actually addressable in the sorting process employing a given number of sorting cycles, and is well below the maximum number addressable in the sorting process employing the next higher number of sorting cycles.
Situations of this sort can be handled by either increasing the number of sorting cycles, increasing the number of sorting machine outputs, or dividing the mail batch into two or more sub-batches for processing separately.
All three solutions, however, are unfeasible for various reasons.
In particular, increasing the number of sorting cycles results in poor utilization of the machine, as well as increased processing time and cost; increasing the number of machine outputs makes for higher production cost of the machine, requires more floor space, and is difficult to implement and decidedly expensive in the case of machines already built and installed; while dividing the mail batch into two or more sub-batches may not be compatible with end user requirements, and anyway calls for redefining pre-sorting routines to generate the sub-batches, and also results in increased processing time and cost.
Situations may also arise in which the number of delivery locations to be addressed is comparable with the maximum number actually addressable in the sorting process employing a given number of sorting cycles, but certain delivery locations have such a high mail traffic as to fill the respective machine outputs on their own.
Situations of this sort invariably result in inefficient processing, on account of the fact that, by filling a respective machine output on their own, the mail items of such delivery locations, after the first sorting cycle, are substantially only moved from one output to another without undergoing any real sorting process.
It is an object of the present invention to provide a method of optimizing a mail sorting process in particular sorting machine operating situations of the type described above.
According to the present invention, there is provided a method of optimizing a mail sorting process, as claimed in claim 1.